Segmented light or optical power emitting device with fully converting wavelength converting material and methods of operation

ABSTRACT

A segmented light or optical power emitting device and an illumination device are described. The segmented device includes a die having a light or optical power emitting semiconductor structure that includes an active layer disposed between an n-layer and a p-layer. Trenches are formed in at least the semiconductor structure and separate the die into individually addressable segments. The active layer emits light or optical power having a first color point or spectrum. At least one wavelength converting layer is adjacent the die and converts the light or optical power to light or optical power having at least one second color point or spectrum and limits an energy ratio of the pump light or optical power that passes through the at least one wavelength converting layer unconverted to total light or optical power emitted by the light or optical power emitting device to less than 10%.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/803,803, filed Nov. 5, 2017, which claims the benefit of U.S.Provisional Patent Application No. 62/418,447, filed Nov. 7, 2016, whichis incorporated by reference as if fully set forth.

BACKGROUND

Semiconductor light-emitting devices or optical power emitting devices(such as devices that emit ultraviolet (UV) or infrared (IR) opticalpower), including light emitting diodes, resonant cavity light emittingdiodes, vertical cavity laser diodes, and edge emitting lasers are amongthe most efficient light sources currently available. Due to theircompact size and lower power requirements, for example, semiconductorlight or optical power emitting devices (referred to herein as LEDs forsimplicity) are attractive candidates for light sources, such as cameraflashes, for hand-held battery-powered devices, such as cameras and cellphones. They may also be used for torch for video, and for generalillumination, such as home, shop, office and studio lighting,theater/stage lighting and architectural lighting. A single LED oftenprovides light that is less bright than a typical light source, and,therefore, arrays of LEDs are often used for such applications.

SUMMARY

A segmented light or optical power emitting device and an illuminationdevice are described. The segmented device includes a die having a lightor optical power emitting semiconductor structure that includes anactive layer disposed between an n-layer and a p-layer. Trenches areformed in at least the semiconductor structure and separate the die intoindividually addressable segments. The active layer emits light oroptical power having a first color point or spectrum. At least onewavelength converting layer is adjacent the die and converts the lightor optical power to light or optical power having at least one secondcolor point or spectrum and limits an energy ratio of the pump light oroptical power that passes through the at least one wavelength convertinglayer unconverted to total light or optical power emitted by the lightor optical power emitting device to less than 10%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram providing a view of a cross section of an examplesegmented LED taken across three addressable segments with a singlefully converting wavelength converting layer over all segments;

FIG. 1B is a diagram providing a view of a cross-section of an examplesegmented LED taken across three addressable segments with individualfully converting wavelength converting layers that are not fullyoptically sealed and are respectively disposed over one or moresegments;

FIG. 1C is a diagram providing a view of a cross-section of an examplesegmented LED taken across three addressable segments with a singlefully converting wavelength converting layer that is partially segmentedand disposed over all segments;

FIG. 1D is a diagram providing a view of a cross-section of an examplesegmented LED taken across three addressable segments with a scatteringor off state white layer overlay;

FIG. 1E is a diagram providing a view of a cross-section of an examplesegmented LED taken across three addressable segments with a partiallysegmented scattering or off state white layer overlay;

FIG. 1F is a diagram providing a view of a cross-section of an examplesegmented directed blue LED taken across three addressable segments;

FIG. 2 is a diagram of the back of an example smart phone;

FIGS. 3A and 3B are diagrams of example flash modules that include dualsegmented LEDs;

FIG. 3C is a diagram of an example flash module that includes threesegmented LEDs;

FIG. 4 is a block diagram of an example imaging system for use in acamera, such as a smart phone camera;

FIG. 5 is a flow diagram of an example method of operating one or moresegmented LEDs where light or optical power output by the segments ismixed a short distance from the one or more LEDs;

FIGS. 6A, 6B, 6C and 6D are diagrams of example imaging systems showingdifferent arrangements of Fresnel lenses for projecting an image orimages of the one or more segmented LEDs onto a scene to bephotographed;

FIGS. 7A, 7B, 8A, 8B, 9A, 9B, 10A and 10B are diagrams illustratingexamples of different ways segments of one or more segmented LEDs may beaddressed with a single current or varying currents to illuminate atarget object in a scene differently; and

FIG. 11 is a flow diagram of an example method of operating one or moresegmented LEDs where light output by the segments is projected onto thescene.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A segmented semiconductor light or optical power emitting device(referred to herein as LEDs for simplicity) is described herein thatincludes a single semiconductor die with trenches formed therein thatelectrically insulate individual segments of the die from one another.Each segment may be individually contacted and coupled to metal traceson a circuit board such that the segments may be individually addressed.As compared to an array of individual LEDs, a segmented LED as describedherein may be produced via easier manufacturing in the assembly (e.g.,less pick and place steps with precise positioning may be required) andwith greatly reduced cost. Further, a segmented LED may have a reducedvolume (size) than an array of individual LEDs.

In embodiments described herein, a device may incorporate more than onesegmented LED (e.g., a dual LED flash module) where each segmented LEDprovides light of a particular color point or spectrum. Individualsegments of the segmented LEDs may be addressed, while other segmentsremain off, to provide a precise color point or target spectrumcontrolled flash or other output light (such as for torch for video,studio lighting, theater/stage lighting or architectural lighting). Forexample, for a dual LED flash module, segments in a cool white segmentedLED and segments in a warm white segmented LED may be selectivelyaddressed to provide a combined output light that is warmer or coolerdepending on the ambient light. Other colors or spectra of LEDs and/orsegments may also be used to produce a finely tuned color point ortarget spectrum.

The overall brightness level of the flash module or other lightingmodule may be increased or decreased, even with the same drive current,by addressing more or fewer segments in the segmented LEDs. Thebrightness may also be varied by varying the drive current. Further,various lighting effects may be achieved by projecting an image of thesegmented LEDs onto a scene to be photographed and varying thebrightness and/or color point or target spectrum of the flash projectedonto different regions of the scene.

For a segmented LED, or any device that includes multiple LEDs orsegments that are closely spaced, it is likely that at least some of thepump light or optical power (i.e., unconverted light or optical poweremitted by the active layer of an LED) emitted by one LED or segmentwill cross into neighboring LEDs or segments. When this happens,depending on the makeup of the phosphors in the neighboring LED orsegment and the color point or spectrum of the pump light, the lightthat crosses into the neighboring LED or segment may activate itsphosphors. Thus, a neighboring LED or segment that is not beingenergized may emit a pure phosphor color or spectrum. For example, foran array of LEDs or segments emitting blue pump light that are coveredby a Yttrium aluminum garnet (YAG) phosphor layer, a neighboring LED orsegment that is not being energized may light up yellow when blue pumplight from a neighboring LED crosses into it. This phenomenon may beundesirable for a number of reasons, including, for example, that it mayalter the color point or spectrum of the composite light or opticalpower output by the LED or array in applications where the light oroptical power output is blended or may alter the color point or targetspectrum of individual pixels.

Various embodiments are described herein that make use of a fullyconverting wavelength converting layer (e.g., phosphor layer) thatproduces a light output having a desired color point or target spectrumwhile limiting the energy ratio of pump light or optical power thatpasses through the wavelength converting layer unconverted (e.g., bluepump light) to total light or optical power emitted by the LED to lessthan 10% in some embodiments and less than 2% in some embodiments.

When used on a segmented LED where the segments are closely spaced, useof such a fully converting wavelength converting layer will reduce oreliminate the phenomenon of neighboring segments lighting up anundesired color or spectra because the fully converting wavelengthconverting layer will convert any stray light or optical power enteringthe segment to the desired color or spectra. In other words, any straypump light or optical power crossing into a neighboring segment willcause the neighboring LED to emit a lower brightness light or opticalpower having the same color point or target spectrum as the energizedsegment. Further, light traveling in the fully converting wavelengthconverting layer away from an energized segment will still be the samepure phosphor color or spectrum since the phosphor layer may be madethick and/or dense enough so as to not mix in direct-leaking pump lightor optical power (e.g., blue) above the energized segment. This enablesvery accurate color point or target spectrum selection for the segmentedLEDs since optical cross talk between neighboring LEDs or segments doesnot affect the overall color point or target spectrum of the LED. Inembodiments where an image of the segmented LED is projected onto thescene, use of the fully converting wavelength converting layers may alsoprevent optical cross talk between segments from shifting the color orspectrum, particularly at the rim of the segments, which could create avisible colored or spectrum transition at the scene. Thus, the color orspectrum illuminating the scene may be made constant and not varying asa function of the position of the projected image of the scene.

FIG. 1A is a diagram providing a view of a cross section of a segmentedLED 100 taken across three addressable segments. The illustratedsegmented LED 100A includes a semiconductor die that includes a light oroptical power emitting structure formed from a substrate 110, such as asapphire growth substrate, on which one or more n-type layers 130, oneor more p-type layers 140, and a light or optical power emitting activeregion 135 are grown. Trenches 170 a and 170 b are formed in the die(e.g., by etching) to segment the LED 100A into segments 160 a, 160 band 160 c, which are electrically insulated from one another via thetrenches. Each segment 160 is provided with its own contacts 145 and150. The contacts 145 and 150 for each segment contact metal traces (notshown) on a circuit board 165, which allow current to be individuallyapplied to each segment 160 so that the segments may be individuallyaddressed and turned on in any combination and with the same or varyingcurrent level.

The light or optical power emitting semiconductor structure may be anylight or optical power emitting semiconductor structure that emits lightor optical power that may be converted via a wavelength convertingmaterial (e.g., to white light or a broader spectra). An example of sucha semiconductor structure is a III-nitride structure that emits blue,violet or ultraviolet (UV) light, such as a semiconductor structureformed from one or more of binary, ternary, and quaternary alloys ofgallium, aluminum, indium, and nitrogen. Other examples of semiconductorstructures may include semiconductor structures formed from group III-Vmaterials, II-phosphide materials, III-arsenide materials, II-VImaterials, zinc oxide (ZnO), or Silicon (Si)-based materials. Asemiconductor laser may also be used.

The n-type region 130 may be grown on a growth substrate 110 and mayinclude one or more layers of semiconductor material. Such layer orlayers may include different compositions and dopant concentrationsincluding, for example, preparation layers, such as buffer or nucleationlayers, and/or layers designed to facilitate removal of the growthsubstrate. These layers may be n-type or not intentionally doped, or mayeven be p-type device layers. The layers may be designed for particularoptical, material, or electrical properties desirable for the light oroptical power emitting region to efficiently emit light or opticalpower. Like the n-type region 130, the p-type region 140 may includemultiple layers of different composition, thickness, and dopantconcentrations, including layers that are not intentionally doped, orn-type layers. While layer 130 is described herein as the n-type regionand layer 140 is described herein as the p-type region, the n-type andp-type regions could also be switched without departing from the scopeof the embodiments described herein.

The active region 135 may include a single thick or thin light oroptical power emitting layer. Alternatively, the active region 135 maybe a multiple quantum well light or optical power emitting region, whichmay include multiple thin or thick light or optical power emittinglayers separated by barrier layers.

The p-contact 145 may be formed on a surface of the p-type region 140.The p-contact 145 may include multiple conductive layers, such as areflective metal and a guard metal, which may prevent or reduceelectromigration of the reflective metal. The reflective metal may besilver or any other suitable material. The n-contact 150 may be formedin contact with a surface of the n-type region 130 in a region whereportions of the active region 135, the n-type region 140, and thep-contact 145 have been removed to expose at least a portion of thesurface of the n-type region 130.

The n-contact 150 and p-contact 145 are not limited to the arrangementillustrated in FIG. 1A and may be arranged in any number of differentways. In embodiments, one or more n-contact vias may be formed in thelight or optical power emitting semiconductor structure to makeelectrical contact between the n-contact 150 and the n-type layer 130.Alternatively, the n-contact 150 and p-contact 145 may be redistributedto form bond pads with a dielectric/metal stack as known in the art.

In the example illustrated in FIG. 1A, the growth substrate 110 is lefton the die after segmentation. In other embodiments, the growthsubstrate 110 may be removed (e.g., using laser lift-off) to form thinfilm LED segments 160 a, 160 b, and 160 c. A fully converting wavelengthconverting layer 120 a is disposed over the die either in direct contactwith the substrate 110 or thin film segments 160 a, 160 b and 160 c. Asdescribed above, the fully converting wavelength converting layer 120 ais a layer of wavelength converting material that produces a light oroptical power output having a desired color point or target spectrumwhile limiting the energy ratio of pump light or optical power (e.g.,blue pump light) that passes through the wavelength converting layerunconverted to total light or optical power emitted by the lightemitting device to less than 10% in some embodiments and less than 2% insome embodiments. In embodiments, the wavelength converting material maybe any luminescent material, such as a phosphor or phosphor particles ina transparent or translucent binder or matrix that absorbs light oroptical of one wavelength and emits light or optical power of adifferent wavelength. In the example illustrated in FIG. 1, phosphorparticles 125 are disposed in a transparent binder or matrix 126.

The concentration, composition and size of the phosphor particles, aswell as the thickness of the fully converting wavelength convertinglayer 120 a, may be tuned such that light or optical power emitted viathe fully converting wavelength converting layer 120 a may appear to bered, green, cyan, warm white, cool white or any other desired color orspectrum. In embodiments, the fully converting wavelength convertinglayer 120 a may have a thickness between 20 μm and 100 μm. The maximumlayer thickness will be related to the segment sizes. To reduce edgeeffects, the thickness should be ≤⅓ of the segment length. Concentrationof phosphor particles to binder or matrix material may depend on thedeposition technology and may range from 10% by volume to nearly 80% byvolume. The size of the phosphor grains may range from median 1 μm to 50microns. Denser concentrations of phosphor grains, smaller phosphorgrains and thicker wavelength converting layers (i.e., on the upper endof the described ranges) may be used to suppress the pump light oroptical power from passing through the layer unconverted. Thecomposition of the phosphors included in the layer may be selected toproduce the desired color point or target spectrum of light emittedthrough the layer, taking into account that only a small amount of thepump light (e.g., blue light) or optical power (e.g., UV or IR) willpass through. For example, the fully converting wavelength convertinglayer 120 a may emit blue, red and green components. The wavelengthconverting phosphor layers may comprise a combination of phosphors thatare commercially available. Using phosphor converted emission instead ofdirect light is beneficial for many applications, for example, due tothe broader spectrum generated as well as that the semiconductor pumpcan be chosen the same and will have similar behavior in terms of, forexample, current and temperature dependence.

When one or more of the segments 160 is energized by applying current toit via a corresponding trace on the circuit board 165, the one or moreof the segments 160 emit light or optical having a first color orspectrum (color 1). In the example illustrated in FIG. 1A, the segment160 b is energized and emits light or optical power (e.g., ray 127)having the first color or spectrum (color 1), and the phosphors 125 inthe wavelength converting layer 120 a fully convert the light or opticalof the first color or spectrum (color 1) to light of a second color orspectrum (color 2) such that the energy ratio of the pump light oroptical power having the first color or spectrum (color 1) that passesthrough the wavelength converting layer 120 a unconverted to total lightor optical power emitted by the light or optical power emitting device100A is limited to less than 10% in some embodiments and less than 2% insome embodiments.

In embodiments, color or spectrum 1 may be, for example, blue, violet orUV pump, respectively, and color or spectrum 2 may be, for example, oneof a warm white color, a cool white color, red, cyan or green. Inembodiments, the warm white color may have a color point between 1800Kand 2500K and may appear orange in color, and the cool white may appearblue or cyan in color. While embodiments described herein are describedwith respect to the targeted white tuned colors, one of ordinary skillin the art will recognize the second color or spectrum (color 2) may beany color, such as red, green or blue, depending on the application.

FIG. 1B is a diagram providing a view of a cross-section of anotherexample segmented LED 100B taken across three addressable segments. Inthe example illustrated in FIG. 1B, instead of using a single fullyconverting wavelength converting layer 120 a disposed over all segments160, individual fully converting wavelength converting layers 180, 185and 190 are disposed over respective segments or groups of respectivesegments (not shown). The individual fully converting wavelengthconverting layers may not be fully optically sealed to provide partiallysegmented fully converting wavelength converting.

FIG. 1C is a diagram providing a view of a cross-section of anotherexample segmented LED 100C taken across three addressable segments. Inthe example illustrated in FIG. 1C, a single fully converting wavelengthconverting layer 120 b is disposed over all segments 160. However, inFIG. 1C, the fully converting wavelength converting layer 120 b ispartially segmented by forming respective separations 187 a and 187 bbetween neighboring segments 160 a, 160 b and 160 c. The separations 187a and 187 b may be formed, for example, by making laser cuts in thefully converting wavelength converting layer 120 b that do not fully cutthrough the layer 120 b to provide a partially segmented fullyconverting wavelength converting layer 120 b.

FIG. 1D is a diagram providing a view of a cross-section of anotherexample segmented LED 100D taken across three addressable segments 160a, 160 b and 160 c. In the example illustrated in FIG. 1D, the LED 100Dincludes a scattering or off state white layer 195 a disposed over thefully converting wavelength converting layer 120 c. The scattering oroff state white layer 195 a may include particles of TiOX, particles ofother scattering material, or any off state white material, such asparaffin, disposed in an optically transparent material or matrix. Thelayer 195 a may be used to provide scattering of light emitted by theindividual segments, as described in more detail below, and/or toprovide a white appearance to the segmented LED when it is turned off.

FIG. 1E is a diagram providing a view of a cross-section of anotherexample segmented LED 100E taken across three addressable segments 160a, 160 b and 160 c. In the example illustrated in FIG. 1E, thescattering or off state white layer 195 b is partially segmented byrespective separations 197 a and 197 b formed in the layer 195 b.Similar to the embodiment of FIG. 1C, the scattering or off state whitelayer 195 b may be partially segmented by making laser cuts in the layerthat do not fully cut through the layer so as to provide a partiallysegmented scattering or off state white layer 195 b.

FIG. 1F is a diagram providing a view of a cross-section of a directblue segmented LED 100F. In the example illustrated in FIG. 1F, nowavelength converting layer is used, and the pump light or optical isemitted out of the LED in its original color or spectrum (e.g., blue).In embodiments, a scattering layer 199 may be disposed over the segments160, as described in more detail below. The segmented layer may benon-segmented as shown in FIG. 1F or partially segmented as shown inFIG. 1E.

In embodiments where a partially segmented fully converting wavelengthconverting layer and/or a partially segmented scattering or off statewhite layer are used, the full conversion reduces or eliminates risk ofcolor shading while the partial segmentation increases segment tosegment contrast where desirable.

In the embodiments that follow, the segmented LEDs described may be anyof the segmented LEDs described with respect to FIG. 1A, 1B, 1C, 1D, 1Eor 1F or any variant that would be understood by one of ordinary skillin the art. In addition, while the term segmented LED is used, thesegmented LED may be any type of silicon light or optical power emittingdevice, including lasers, and may emit visible or optical power (e.g.,IR spectroscopy where targeted radiation is in the IR range and pumplight or optical power can be UV up to red and may be LED based or laserbased).

FIG. 2 is a diagram of the back of an example smart phone 200. The smartphone 200 illustrated in FIG. 2 has a camera module 210 that may includea lens (240) via which an image sensor unit may capture an image of ascene. The camera module 210 also includes a flash module 250 that mayinclude one or more LEDs, such as multiple LEDs 100. In the exampleillustrated in FIG. 2, the flash module 250 includes two LEDs 220 and230. One of ordinary skill in the art will understand, however, that oneor more LEDs may be used consistent with the embodiments describedherein. Examples of different potential arrangements for the one or moresegmented LEDs in the flash module 250 are provided in FIGS. 3A, 3B, 3C.

FIGS. 3A and 3B are diagrams of example flash modules 250 that includedual LEDs 220 and 230 as in FIG. 2. In the example illustrated in FIG.3A, the flash module 250 a includes a cool white segmented LED 220 a anda warm white segmented LED 230 a. The cool white segmented LED 220 a mayinclude a plurality of addressable segments, all of which may be coveredby a fully converting wavelength converting layer that is tuned to emitlight having a desired color, such as a cyan white color, which may bepumped by UV light, or may be a direct blue or direct cyan emitting LED.Example cyan white wavelength converting layers include BAM (Euactivated Ba-Mg-Aluminate), ZnS:Ag, or Sr3MgSi2O8:Eu (SMS). Note thatfor the visible application, the UV pumped cyan wavelength convertinglayer does not necessarily have to be fully converting if theapplication does not detect UV light. However it is still preferred forefficiency and safety reasons.

The warm white segmented LED 230 a may similarly include a plurality ofaddressable segments, all of which may be covered by a fully convertingwavelength converting layer that is tuned to emit light having colorpoint in the warm white orange range. Example warm white fullyconverting wavelength converting layers may include BSSN((Ba,Sr)2Si5N8:Eu), YAG:Ce, and Sr[LiAl3N4]:Eu2+.

In the example illustrated in FIG. 3B, the flash module 250 b includes ared segmented LED 220 b and a cyan segmented LED 230 b. The redsegmented LED 220 b may include a plurality of addressable segments, allof which may be covered by a fully converting wavelength convertinglayer that is tuned to emit red light. Example red fully convertingwavelength converting layers may include_BSSN ((Ba,Sr)2Si5N8:Eu) orSr[LiAl3N4]:Eu2+. The cyan segmented LED 230 b may similarly include aplurality of addressable segments, all of which may be covered by afully converting wavelength converting layer that is tuned to emit cyanlight. An example cyan fully converting wavelength converting layer mayinclude YAG:Ce, and Y,LuAG:Ce.

FIG. 3C is a diagram of an example flash module 250 c that includesthree segmented LEDs 220 c, 230 c and 310. In the example illustrated inFIG. 3C, the flash module 250 c includes a red segmented LED 220 c, agreen segmented LED 230 c and a blue segmented LED 310. The redsegmented LED 220 c may be similar to the red segmented LED 220 b ofFIG. 3B. The green segmented LED 230 c may include a plurality ofaddressable segments, all of which may be covered by a fully convertingwavelength converting layer that is tuned to emit green light. Examplegreen fully converting wavelength converting layers may include YAG:Cephosphor or YLuAG-Ce phosphors.

The blue LED 310 (or a cool white LED in the blue range) may not need awavelength converting layer as the active layer of the LED 310 maydirectly emit blue light. In embodiments, such as in FIG. 3C or FIG. 3A,where a direct blue LED may be used, the LED may include a lightscattering layer, such as a layer of silicone into which TiOx particlesare dispersed. The TiOx layer may be used to tune the source size to thephosphor covered LEDs (such as the red and green LEDs 220C and 230C).The scattering layer may also be used in such an embodiment to diffusethe light or optical power so that luminance distribution and radiationpattern from all the LEDs in the flash module are similar, which mayallow use of the same optics for each LED for proper scene illumination.

One or more segmented LEDs 100 may be used in a flash module 250 of acamera module 210 for a number of different purposes, which aredescribed in more detail below. In embodiments, light or optical poweroutput by the one or more segmented LEDs may be mixed a short distancefrom the LED or LEDs such that the color point or spectrum of theoverall light or optical power output of the flash module 250 may betuned to match ambient lighting. In further embodiments, rather thanmixing the light or optical power output by the segments, light oroptical power from the individual segments of one or more segmented LEDsmay be projected onto the scene to be photographed (e.g., using aFresnel lens). This may be done, for example, to provide more evenlighting at a scene to be photographed, to highlight different regionsof a scene to be photographed, or to vary the color point or spectrum oflight or optical power illuminating different regions of a scene to bephotographed.

FIG. 4 is a block diagram of an example imaging system 400 for use in acamera, such as the smart phone camera module 210 of FIG. 2. The exampleimaging system 400 may be used to provide a flash output having a colorpoint or spectrum that is tuned to the ambient lighting or to offsetundesirable characteristics of the ambient light. The example imagingsystem 400 may also be used to vary the brightness of different segmentsand project an image of one or more segmented LEDs onto a scene to bephotographed.

The example imaging system 400 illustrated in FIG. 4 includes a flashmodule 250 that includes two segmented LEDs 425 and 430, although one ofordinary skill in the art will understand that one or more than twosegmented LEDs may be used in accordance with the embodiments describedherein. The segmented LEDs may be coupled to a driver 420, which maysupply power to the segmented LED or LEDs, as described in more detailbelow. The driver 420 may be coupled to a processor 410 (e.g., amicroprocessor), which may be coupled to receive input from a userinterface 405, an image sensor unit 415 and, optionally, a 3D sensor450. In embodiments, the various circuits that control the segmentedLEDs 425-430, such as the processor 410 and the driver 420, may bereferred to as a controller.

The image sensor unit 425 may be an image sensor used for the purpose ofmeasuring ambient light and/or creating an illumination profile for ascene. Alternatively, the image sensor unit 425 may include the mainimage sensor for the camera. In embodiments, a separate cameracontroller may be part of the image sensor unit 425 and may control theexposure of the image sensor. The user interface 405 may be, forexample, a user-activated input device such as a button that a userpresses to take a picture or a touch screen device. In embodiments,however, user input may not be required, such as where a picture may betaken automatically.

Optical elements 435 and 440 are provided for various purposes and mayvary depending on the application for which they are being used. Inembodiments, the optical elements may be collimating lenses, which maymix the light from corresponding segmented LEDs a short distance fromthe segmented LEDs and focus the combined light on the scene 445. Inembodiments, the optical elements may be Fresnel lenses used to projectimages of corresponding segmented LEDs onto a scene to be photographed445 (as described in more detail below).

The 3D sensor 450, if included, may be any suitable sensor capable ofmaking a 3D profile of a scene to be photographed prior to capturing afinal image of the scene. In embodiments, the 3D sensor 450 may be atime of flight (ToF) camera, and time may be used to calculate thedistance to each object in the scene to be photographed. In embodiments,the 3D sensor 450 may be a structured light sensor, which may include aprojection device that projects a specially designed pattern of lightonto the scene. A camera may also be included in the structured lightsensor to measure the position of each part of the light patternreflected from the objects in the scene and determine the distance tothe objects by triangulation. In embodiments, the 3D sensor 450 may beone or more auxiliary cameras positioned at a distance from each otherin the body of a device. By comparing the position of the objects asseen by the auxiliary camera or cameras, distances to each object may bedetermined by triangulation. In embodiments, the 3D sensor 450 may usethe autofocus signal of the main camera in the device (e.g., the imagesensor unit 415). While scanning the focus position of the camera lens,the system may detect at which positions which parts of the scene are infocus. A 3D profile of the scene may then be built by translating thecorresponding lens positions into the distances to the objects that arein focus for these positions. A suitable autofocus signal may be derivedby conventional methods, such as by measuring the contrast or by usingphase detection sensors within the camera sensor. When phase detectionsensors are used, in some embodiments, for optimal functioning of theflash module, the positions of individual phase detection sensors maycorrespond to areas illuminated by separate segments of one or moresegmented light emitting device, as described below.

In embodiments where light from multiple segments in a segmented lightemitting device is mixed before the light is focused onto the scene, theprocessor 410 may determine the color point of the ambient lighting andcontrol the driver 420 to tune the mixed light output by the one or moresegmented LEDs 425-430 to match the color point of the ambient lightingor to offset undesirable characteristics of the ambient light. This maybe done by controlling the driver 420 to address particular segments ofeach of the segmented LEDs or the single LED such that each colorrepresents a particular percentage of the overall light output. By wayof example, if the segmented light emitting device 425 is a warm whitedevice and the segmented light emitting device 430 is a cool whitedevice, and the color point of the ambient lighting represents a colorpoint that is 75% cool and 25% warm, 75% of the segments in the coolwhite device 430 may be addressed and 25% of the segments in the warmwhite device 425 may be addressed. In such an embodiment, the samecurrent may be applied to each addressed segment to maintain an accuratecolor point. In other embodiments, different currents may be applied todifferent addressed segments to make them emit brighter light, and theprocessor 410 will account for the difference in brightness whendetermining how many segments in each segmented light emitting device toaddress. The processor 410 may behave similarly when different numbersof segmented LEDs are used and when segmented LEDs of different colorsare used.

FIG. 5 is a flow diagram 500 of an example method of operating one ormore segmented light emitting devices where light output by the segmentsis mixed. In the example illustrated in FIG. 5, the method includesmeasuring the color point of the ambient lighting (510). This may bedone according to any method known in the art, such as by controllingthe image sensor unit 415 to initially image the scene 445 and analyzingthe image to determine the color point of the ambient light. Thesegments to address for each of the one or more segmented light emittingdevices may then be determined (520). This may be done, for example, bythe processor 410 accessing a look up table, which may tell theprocessor 410 which segments to address based on the determined colorpoint of the ambient light to either match the color point of theambient light or offset particular characteristics of light (such asgreenish characteristics of fluorescent light). The processor 410 maythen control the driver 420 to address the determined segments (530).

In embodiments where an image of the segmented LED or LEDs is projectedonto the scene 445, the processor 410 may determine an optimalilluminance profile for the scene 445 and control the driver 420 toaddress certain segments and use certain currents to drive particularsegments based on the determined optimal illuminance profile. One ormore Fresnel lenses may be used to project an image of each segmentedlight emitting device onto the scene to be photographed 445.

FIGS. 6A, 6B, 6C and 6D are diagrams of example imaging systems showingdifferent arrangements of segmented light emitting devices and Fresnellenses for projecting an image or images of the one or more segmentedLEDs onto an image to be photographed 445. In FIGS. 6A and 6B, theimaging systems 600A and 600B each include a respective single segmentedLED 605A/605B and a respective Fresnel lens 615A/615B that are used toilluminate a scene 610A/610B. As can be seen in the illustrations,certain segments of the segmented light emitting devices 605A/605B areactivated (indicated with an X) and the image of the segmented LED605A/605B is projected, using the Fresnel lens 615A/615B, such that amirror image of the pattern produced by activating the segmentsindicated with an X is projected onto the scene 610A/610B (light patternprojected onto the scene is indicated with Xs in the figures).

In FIGS. 6C and 6D, two segmented LEDs and two corresponding Fresnellenses are used. In FIG. 6C, the imaging system 600C includes twosegmented LEDs 605C and 606A and two Fresnel lenses 615C and 616A. TheFresnel lenses 615C and 616A are each configured to project an image ofa respective segmented LED 605C and 606A onto a corresponding region ofthe scene 620. In the example illustrated in FIG. 6C, the lens 615Cprojects an image of the segmented LED 605C onto an upper region 620 ofthe scene 610A and the lens 616A projects an image of the segmented LED606A onto a lower region 625 of the scene 610A. As described in moredetail below, this can enable the system 600C to achieve differentlighting effects, such as projecting a warmer light onto a lower portionof the scene and a cooler light onto an upper portion of the scene. Insome embodiments, the segmented LEDs 605C and 606A may illuminateoverlapping portions of the scene 610A in order to provide more light tothe overlapping parts. For example, the arrays projected onto the scenemay overlap in the center of the scene, which often requires more lightthan the edges of the scene.

In FIG. 6D, the imaging system 600D includes two segmented LEDs 605D and606B and two Fresnel lenses 615D and 616B. In the example illustrated inFIG. 6D, the system 600D may be color tunable. The segmented lightemitting devices 605D and 606B emit respective beams 630 and 635, whichoverlap when illuminating the scene 610D. The processor 410 maycalculate the appropriate current to be supplied to each segmented LED605D/606B such that the sum of light from the arrays has the desiredilluminance and color point for each portion of the scene. Additionalsegmented LEDs (or light emitters) emitting additional colors may beadded consistent with the embodiments described herein.

FIGS. 7A, 7B, 8A, 8B, 9A, 9B, 10A and 10B provide examples of differentways segments of one or more segmented LEDs may be addressed with asingle current or varying currents to illuminate a target object 710 ina scene 700 differently. More details are provided in PCT Appln. Pub.No. WO/2017/080875, filed Nov. 2, 2016, which is incorporated byreference as if fully set forth herein. In embodiments, the target 710,identified by the dashed circle in the figures, may require more lightthan the rest of the scene, according to a calculated illuminationprofile.

One consideration in distributing current to be applied to one or moresegments of a segmented LED is that, for some devices, such as mobile orother battery-powered devices, the maximum amount of current availablefor the flash module 250 is limited by the capabilities of the devicebattery. When defining drive current levels to all the segments, thesystem may take into account the maximum available current and definethe drive current level for each segment such that the total drivecurrent does not exceed the maximum while the correct ratio of intensitybetween the segments is maintained and total light output is maximized.

FIG. 7A illustrates how the scene 700A is illuminated when all segments720A of a segmented LED 750A (illustrated in FIG. 7B) are addressed andsupplied with the same amount of current. As illustrated, the center ofthe scene is more illuminated than the edges and, in particular, theportion of the target 710A located near the center of the scene is moreilluminated than the portion of the target 710A located near the edge ofthe scene.

FIG. 8A illustrates how the scene 700B is illuminated when a subset ofthe segments 720B, and particularly three segments 722, 724 and 726 inthe middle and lower left hand region of the segmented LED 750B(illustrated in FIG. 8B) are addressed and supplied with the samecurrent while the rest of the segments 720B are not addressed and aresupplied with no current. As illustrated in FIG. 8A, the right side ofthe scene 700B corresponding roughly to the target 710B is more brightlyilluminated than the rest of the scene 700B. The current density for theaddressed segments 722, 724 and 726 may be three times higher than theaddressed segments in FIG. 7B where all segments 720A are supplied withthe same current. Therefore, the illuminance of the target 710B in FIG.8A may be about 1.6 times higher than the illuminance of the target 710Ain FIG. 7A. To obtain higher illuminance, fewer segments may beaddressed.

FIG. 9A illustrates how the scene 700C is illuminated when a singlesegment 720C is addressed and supplied with the maximum current whilethe other eight segments 720C are not addressed and supplied with nocurrent. In the example illustrated in FIG. 9B, the segment 728 in thecenter of the left-most column is addressed and provided with themaximum current. As illustrated in FIG. 9A, the right side of the scene700C corresponding roughly to the target is more brightly illuminatedthan the rest of the scene 700C, although the highly illuminated spot issmaller than in FIG. 8A, for example. The illuminance of the target inFIG. 8A, however, is greater than the illuminance of the target in FIG.7A, for example.

In embodiments, to improve uniformity of illuminance across the entiretarget 710, the processor 410 may control the driver 420 to vary thecurrent supplied to different addressed segments.

FIG. 10A illustrates how the scene 700D is illuminated when foursegments 720D are addressed and supplied with varying levels of currentand five segments 720D are not addressed and are supplied with nocurrent. In the example illustrated in FIG. 10B, the center segment 730in the left-most column is supplied with four times more current thanthe bottom segment 736 in the center column and with twice as muchcurrent as the center segment 732 and the bottom segment 734 in theleft-most column. The top row and right-most column of segments 720Dreceive no current, as illustrated in FIG. 10B. As illustrated in FIG.10A, the right side of the scene 700D corresponding roughly to thetarget 710D is more brightly illuminated than the rest of the scene700D, and the illuminance of the target 710D is more uniform than in,for example, FIGS. 7A, 8A, and 9A.

In other embodiments, when the processor 410 receives an instructionfrom, for example, the user interface 405, to zoom in the camera lens,segments near the center of the segmented LED may receive more current.In embodiments, illuminance at the center of the scene may be increasedby 1.15 times over the center of the scene illustrated in FIG. 7A. Inother embodiments, illuminance at the center of the scene may beincreased by 2.2 times over the center of the scene illustrated in FIG.7A. In contrast, when the processor 410 receives an instruction from,for example, the user interface 405, to zoom out the camera lens,segments near the edges of the segmented LED may receive more current.For wide angle applications, the segments at the edges of the segmentedLED may receive equal current while the center segment may receive nocurrent. In embodiments, illuminance at the center of the scene may bereduced to 0.85 times the illuminance at the center of the scene in FIG.7A, for example.

The system 400 may also be used to illuminate multiple targets, forexample, by providing current only to segments corresponding to eachtarget or by providing more current to segments corresponding to eachtarget. Additionally, the system 400 may be used to reduce overexposurein a scene containing elements that are close to the camera and far fromthe camera by providing current only to the segments corresponding tothe elements far from the camera or by providing more current tosegments corresponding to the elements far from the camera. Whileembodiments described herein provide for automated methods ofcontrolling flash color point and brightness distribution, the userinterface 405 may also be used to provide a user with personal controlover the flash color point and brightness distribution.

While the embodiments described above, for example with respect to FIGS.7A, 7B, 8A, 8B, 9A, 9B, 10A and 10B, are described with respect to asingle segmented LED, one of ordinary skill in the art will recognizethat they are equally applicable to embodiments where more than onesegmented LED is included in a flash module. For example, if twosegmented LEDs emit a different white light color point, the samesegments in each may be addressed to ensure good overlapping of theLEDs' images over the scene to ensure a uniform illuminating color andthe relative amounts of each color point to the combined illuminationmay be adjusted, in some embodiments, by varying the current to one ofthe LEDs.

The illuminance values for the examples provided above are calculatedfor the illustrated 3×3 segmented LED with a single Fresnel lens.However, they can be adapted for segmented LEDs having different numbersof segments and for multiple segmented LEDs with multiple Fresnellenses, as described in embodiments above. The light output of eachsegment may be controlled by the driver current of the segmented LED orby pulse duration with a fixed current.

FIG. 11 is a flow diagram of an example method 1100 of operating one ormore segmented LED where light output by the segments is projected ontothe scene. In the example illustrated in FIG. 11, the method includesmeasuring a scene to be photographed (1110) and creating an illuminationprofile for a scene (1120). The driver 420 may then be controlled toaddress particular segments of the one or more segmented LED to applyparticular currents to the addressed segments based on the illuminationprofile (1130).

In embodiments, the scene may be measured using one or more of 3D sensor450 and the image sensor unit 415. In one example, the user interface405 may provide an instruction to the processor 410 indicating that apicture is to be taken. The image sensor unit 415 or 3D sensor 450 maycapture a first preliminary image of the scene 445, corresponding to thefield of view of the image sensor unit 415, with the flash module 250turned off. The flash module 250 may then be turned on in a lower lightoutput mode (e.g., torch mode). At this time, the illuminance profile ofthe flash module may be set to uniform, meaning that all regions of thescene 445 are illuminated with a known illumination profile. A secondpreliminary image may then be captured using the image sensor unit 415or 3D sensor 450 while the flash module 250 continues to be on with theuniform illuminance profile and low brightness. The processor 410 maythen calculate the optimum brightness for all regions of the scene 445to achieve optimal exposure. This may be done, for example, bysubtracting the pixel brightness values of the first preliminary imagefrom the respective pixel brightness values of the second preliminaryimage and scaling the differences to achieve the optimal exposurelevels. The final image of the scene 445 may then be captured by theimage sensor unit 415 with the flash module 250 activated according tothe determined illuminance profile.

In another example, the processor 410 may receive an input, such as fromthe user interface 405, indicating that a picture should be taken. Theprocessor 410 may then control the image sensor unit 415 or 3D sensor450 to capture a first preliminary image of the scene 445 correspondingto the field of view of the image sensor unit 415 with the flash module250 turned off. A 3D profile of the scene 445 may then be generated. Forexample, the 3D sensor 450 may generate the 3D profile of the scene orthe 3D sensor 450 may sense data about the scene 450 and transmit thedata to the processor 410, which may generate the 3D profile of thescene. The processor 410 may then calculate the optimum brightness forall parts of the scene 445 to achieve optimal exposure. Based on thecalculation, the processor 410 may control the driver 420 to illuminatethe scene 445 using the flash module 250.

In yet another example, the processor 410 may receive an input, such asfrom the user interface 405, indicating that a picture should be taken.The processor 410 may then control the image sensor unit 415 or the 3Dsensor 450 to capture a first preliminary image of the scene 445corresponding to the field of view of the image sensor unit 415 with theflash module turned off. A 3D profile of the scene 445 may then begenerated. At this time, the illuminance profile of the flash module maybe kept uniform, meaning that all portions of the scene 445 areilluminated. A second preliminary image may then be captured with theflash module 250 in torch mode. The processor 410 may then calculate theoptimum brightness for all portions of the scene 445 to achieve optimalexposure based on the two preliminary images captured and 3D profile (asdescribed in the second example above). The image sensor unit 415 maythen capture the final image with the flash module 250 activatedaccording to the calculated illuminance profile.

One or more illumination modes may also be defined for embodimentsdescribed herein. For example, in a first group of illumination modes,illumination from the flash module 250 may be distributed across thescene to achieve the most homogenously useful illuminated picture. Inparticular, in some embodiments, overexposure may be minimized, such asin the case where the foreground is well illuminated by ambient light,all light may be directed from the flash module 250 to the background ofthe scene 445. In some embodiments, the flash module 250 may act as afill in flash, such as where the background is well illuminated by theambient light and all light from the flash module 250 is directed to theforeground. In some embodiments, where the foreground and background areevenly illuminated by ambient lighting, light from the flash module 250may be sent mostly to the background. In some embodiments, where theforeground is dark, light from the flash module 250 may illuminate theforeground just enough to generate a good picture and the rest of thelight from the light module is sent to the background.

In embodiments, in a second group of illumination modes, selectedobjects may be illuminated. In particular, in some embodiments, incombination with face recognition, faces (or other objects) may beweighted highest for the best illumination. In some embodiments, incombination with face recognition, background around faces (or otherobjects) may receive less light, for example to increase contrastbetween the illuminated face or other object and the background nearestthe face or other object. In some embodiments, selected zones mayinclude zoomed-in images or otherwise identified portions of the scene445. In some embodiments, for pictures of, for example, business cards,light from the flash module 250 may be emitted with a very highuniformity profile.

While specific embodiments are described above with respect to LEDflash, one or more segmented LEDs with fully converting wavelengthconverting layers, as in any of the embodiments above, may be used inother types of general lighting, such as torch for video, studiolighting, theater/stage lighting or architectural lighting. Further,while specific pump light sources are described, any suitable pump lightmay be used for the segmented LEDs, including non-visible optical power.Also, while the embodiments address the visible illuminationapplication, other cases, such as IR irradiation and IR spectroscopyincluding a wavelength conversion step, may also benefit from thewell-defined emitted spectrum without pump light leakage. In thesenon-visible optical power applications, instead of converting the colorpoint of light using the fully converting wavelength converting layer,the spectrum is converted to a target spectrum. Further, in instanceswhere only visible light emission or conversion are described, it isintended that optical power emission or conversion may be substituted.

Having described the embodiments in detail, those skilled in the artwill appreciate that, given the present description, modifications maybe made to the embodiments described herein without departing from thespirit of the inventive concept. Therefore, it is not intended that thescope of the invention be limited to the specific embodimentsillustrated and described. In addition, the methods described herein maybe implemented in a computer program, software, or firmware incorporatedin a computer-readable medium for execution by a computer or processor.Examples of computer-readable media include electronic signals(transmitted over wired or wireless connections) and computer-readablestorage media. Examples of computer-readable storage media include, butare not limited to, a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

1. (canceled)
 2. A light emitting device comprising: a die comprising aplurality of individually addressable segments separated by a pluralityof trenches, each segment comprising a semiconductor structureconfigured to emit radiation; and a wavelength converting layer coupledwith the die, the wavelength converting layer having a binder materialcontaining a phosphor, a density of the phosphor limiting a ratio ofenergy of the radiation exiting the wavelength converting layer toenergy of the radiation impinging on the wavelength converting layer tobe less than 10%.
 3. The device of claim 2, wherein a concentration ofthe phosphor in the binder is close to 80% per volume.
 4. The device ofclaim 2, wherein a size of grains of the phosphor range from a median of1 μm to 50 microns
 5. The device of claim 2, wherein the wavelengthconverting layer comprises different phosphors that together produce adesired color point or target spectrum of the converted light, takinginto account an amount of the radiation exiting the wavelengthconverting layer.
 6. The device of claim 2, wherein a thickness of eachsegment is less than about ⅓ of a length of the segment.
 7. The deviceof claim 2, wherein the wavelength converting layer comprisesseparations that do not fully cut through the wavelength convertinglayer and that arc vertically aligned with the trenches such that theseparations are disposed between the segments.
 8. The device of claim 7,wherein the separations are formed in a surface of the wavelengthconverting layer opposing a surface of the wavelength converting layerfacing the die.
 9. The device of claim 2, further comprising: ascattering layer disposed over the converting wavelength convertinglayer, the scattering layer comprising particles of an off state whitematerial disposed in an optically transparent material to providescattering of light emitted by the plurality of individually addressablesegments and to provide a white appearance to the plurality ofindividually addressable segments when deactivated.
 10. The device ofclaim 9, wherein the scattering layer comprises separations that do notfully cut through the scattering layer and that are vertically alignedwith the trenches such that the separations are disposed between thesegments.
 11. The device of claim 10, wherein the separations are formedin a surface of the scattering layer opposing a surface of thescattering layer facing the wavelength converting layer.
 12. The deviceof claim 2, further comprising: a substrate on which the individuallyaddressable segments are disposed, wherein the wavelength convertinglayer is coupled with the individually addressable segments through thesubstrate, wherein each individually addressable segment comprises ann-layer, a p-layer, and an active layer, wherein the individuallyaddressable segments are electrically driven by a plurality of contactssuch that for each individually addressable segment a unique n-contactcontacts the p-layer and a unique p-contact contacts the p-layer, andwherein the trenches are formed through the p-layer, the active layerand at least a portion of the n-layer.
 13. An illumination devicecomprising: a first light emitting structure comprising: a first diecomprising a first plurality of individually addressable segmentsseparated by a first plurality of trenches, each of the first pluralityof individually addressable segments comprising a first semiconductorstructure configured to emit first radiation; and a first wavelengthconverting layer coupled with the first die, the first wavelengthconverting layer having a binder material containing a phosphor, adensity of the phosphor limiting a ratio of energy of the firstradiation exiting the first wavelength converting layer to energy of thefirst radiation impinging on the first wavelength converting layer to beless than 10%; and a second light emitting structure comprising a seconddie comprising a second plurality of individually addressable segmentsseparated by a second plurality of trenches, each of the secondplurality of individually addressable segments comprising a secondsemiconductor structure configured to emit second radiation.
 14. Theillumination device of claim 13, further comprising: a second wavelengthconverting layer coupled with the second die, the second wavelengthconverting layer having a binder material containing a phosphor, adensity of the phosphor of the second wavelength converting layerlimiting a ratio of energy of the second radiation exiting the secondwavelength converting layer to energy of the second radiation impingingon the second wavelength converting layer to be less than 10%, lightemitted from the first and second wavelength converting layers beingdifferent.
 15. The illumination device of claim 14, wherein at least oneof the first or second wavelength converting layer comprises differentphosphors that together produce a desired color point or target spectrumof the light exiting therefrom, taking into account an amount of theradiation passing therethrough.
 16. The illumination device of claim 14,wherein: at least one of the first or second wavelength converting layercomprises separations formed in a surface of the at least one of thefirst or second wavelength converting layer opposing a surface of the atleast one of the first or second wavelength converting layer facing anassociated die, the separations do not fully cut through the at leastone of the first or second wavelength converting layer, and theseparations are vertically aligned with the trenches such that theseparations are disposed between the segments.
 17. The illuminationdevice of claim 14, further comprising: a first scattering layerdisposed over one of the first or second wavelength converting layer,wherein the first scattering layer comprises particles of an off statewhite material disposed in an optically transparent material to providescattering of light emitted by one of the first or second plurality ofindividually addressable segments associated with the one of the firstor second wavelength converting layer and to provide a white appearanceto the one of the first or second plurality of individually addressablesegments when the one of the first or second plurality of individuallyaddressable segments is deactivated.
 18. The illumination device ofclaim 17, wherein: the first scattering layer is partially segmented byseparations, the separations are formed in a surface of the firstscattering layer opposing a surface of the first scattering layer facingthe one of the first or second wavelength converting layer and do notfully cut through the first scattering layer, and the separations areformed between neighboring segments of the one of the first or secondplurality of individually addressable segments.
 19. The illuminationdevice of claim 17, further comprising: a second scattering layerdisposed over another of the first or second wavelength convertinglayer, wherein the second scattering layer comprises particles of theoff state white material disposed in the optically transparent materialto provide scattering of light emitted by another of the first or secondplurality of individually addressable segments associated with the otherof the first or second wavelength converting layer and to provide awhite appearance to the other of the first or second plurality ofindividually addressable segments when the other of the first or secondplurality of individually addressable segments is deactivated.
 20. Theillumination device of claim 13, wherein a concentration of the phosphorin the binder is close to 80% per volume.
 21. The illumination device ofclaim 13, wherein for each of the first and second plurality of segmentsa thickness of the segment is less than about ⅓ of a length of thesegment.
 22. The illumination device of claim 13, further comprising: anoptical element configured to mix light output from the first and secondlight emitting structures and provide the mixed light onto a scene to bephotographed; and a controller configured to address any of a pluralityof different combinations of the first and second plurality ofindividually addressable segments such that the mixed light provided tothe scene has a determined color point based on ambient lighting.
 23. Anillumination device comprising: first and second independent lightemitting structures, each of the first and second light emittingstructures comprising: a plurality of individually addressable segmentsseparated by a plurality of trenches and configured to emit radiation ofa particular wavelength; and a wavelength converting layer overassociated segments, the wavelength converting layer having a bindermaterial containing a phosphor, a density of the phosphor limiting aratio of energy of the radiation exiting the wavelength converting layerto energy of the radiation impinging on the wavelength converting layerto be less than 10% wherein the first and second light emittingstructures are configured to emit different wavelengths.
 24. Theillumination device of claim 23, wherein: each wavelength convertingcomprises separations formed in a surface of the wavelength convertinglayer that do not fully cut through the wavelength converting layer, andthe separations are vertically aligned with the trenches such that theseparations are disposed between the segments.
 25. The illuminationdevice of claim 23, wherein: each light emitting structure furthercomprises a scattering layer disposed over the converting layer, thescattering layer comprises particles of an off state white materialdisposed in an optically transparent material to provide scattering oflight emitted by the segments and to provide a white appearance to thesegments when the segments are deactivated.
 26. The illumination deviceof claim 23, wherein: each scattering layer comprises separations formedin a surface of the scattering layer that do not fully cut through thescattering layer, and the separations are vertically aligned with thetrenches such that the separations are disposed between the segments.